ac not working
 

I have a 98 318ti auto. The a/c will not come on. Car ran hot, had a defective auxiliary fan and cracked plastic pipes. Replaced pipes and T-stat and bled system runs good not over heating. Auxiliary fan was replaced with wrecking yard unit, close but not exact. Original has blue, tan and black with blue stripe. Replacement has red, green and black wires. Low speed fan comes on at idle when needed. THE A/C DOES NOT COME ON NOW!!! It did, with high speed fan a couple of times. The fuse under the dash has blown several times, before and after auxiliary fan replacement. The green a/c light comes on, warm air blows from vents but the compressor does not ingage. I have jumpered out the compressor to 12 volts to test and it does spin. I am melting here in Alabama so any help would be welcome. Thank you in advance,

Vic

A/C pressure switch or fans relays.

Thank you for the response. How would you check the pressure switch, and relays??

I just fixed mine today with a fuse. Got lucky I know, but it doesn't hurt to check the basic stuff first.

does anyone have any ideas how I could check the ac pressure switch?

Check it with a ohm meter for a dead short. If it does then it is good since it is not turning on. I would look elsewhere though since it is blowing fuses.

How long does a fuse last? does it blow right away or after it runs a while? What fuse is blowing?

More details before I can help.

You can jumper the pressure switch plug to bypass it. The compressor will not come on without enough freon in the system (pressure switch open). Just two ideas about the pressure switch

Took the car to a shop yesterday to get checked, charge ok steady not leaking, the relay is clicking when turned on and off, the ac compressor will spin when jumped out. The shop seems to think that since the auxiliary fan was replaced with a used similar fan that might be the problem. They thought maybe even though it looks like the fan i replaced it might not work with the ac/ecm, the wiring ends and wire colors are different. The low speed fan does come on when needed, but the high speed and ac will not come on. What do you think?

Maybe but I doubt it. I don't think there is a sensor to check if the high speed fan is there or operation before the a/c comes on. Maybe I'm wrong and putting the right fan in there will make it work but my a/c will come on if the fan plug is disconnected...

I remember the fuse for the AC kept blowing on my Ti. Did a little research and found that by pulling the sensor off to the water reserve for the wipers, changing the blown fuse, turning the car back on and turning the a/c back on, my problem was solved. Put the sensor back in for the water reserve after you turn the AC back on. Hope that works.

Thank you Iwill give it a try this evening.

Well that didnt seem to do the trick, any other ideas.

The AC compressor clutch might be grounding out where the compressor clutch wiring plugs in near the compressor. Happened in my case and this was blowing the fuse intermittently. Sometimes the AC would run a bit prior to the fuse blowing. Sometimes not.

In my case the grounding occurred in the plug or in the area very near the plug. I couldn't remove the plug for a permanent fix so I never determined the exact location.

I managed to keep the plug from grounding out by slightly bending it until the short was gone and then fixing the plug in that position. Not the best solution, but it is still holding up.:rolleyes:

Might be worth checking for this problem.

Thanks, I will give it a look.

I've had my 98 ti for 2 years now and the A/C never worked. I just recently decided to troubleshoot it. Fuse #39 was blown and my safety pressure switch (same switch xxxJohnBoyxxx was referring to) wasn't seeing enough pressure. I jumpered the compressor relay to force the compressor on so I could recharge the system. Only after recharging with a full can of r-134a, would the safety pressure switch engage. After that it worked.

Someone posted this tutorial and it helped: http://blog.bavauto.com/bmw-e36/bmw-...not-turning-on

Have you checked all of your fuses yet? You should have 12V on terminal 30 of the compressor relay at all times. If you need any wiring diagrams, message me and I'll send them to you. Hope this helps

Thank you for the information, I will give it a look tonight.